Radio receiver



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Jan. 13, 1942. J. v. FILL RADIO RECEIVER Filed March 3, 1959 PatentedJan. 13, 1942 mimo nncnrvan John v. Fill, Dobbs Ferry, N. Y., asslgnorto Ferro- Corporation of America, Hastings on Endson, N. Y., acorporation of Delaware Application March a, 1939, Serial im-zsasia 1Claim. I (or. 111-442) This invention relates to radio receivers andparticularly to permeability tuned high frequency circuits for radioreceivers.

The usual tuning controls for manual orautomatic operation take the formof a rotatable shaft but the movable coil or core of a permeabilitytuned circuit travels in a straight line. The prior proposals forconverting the rotary motion of the control shaft into a linear motionof the coil or core have not been entirely satisfactory.

An object of this invention is to provide a radio receiver having simpleand inexpensive tuning units includingone or more permeability tunedcircuits, a tuning shaft, and relatively stiff but resilient couplingsbetween a crank arm on the shaft and the movable element of the tunedcircuit or circuits. An object is to provide a permeability tunedcircuit including a coil on a tubular form of insulating material, amagnetic core slidable in the form and having a stiff wire extendingaxially therefrom, a control shaft extending normal to and spaced fromthe axis of the core and coil, and an operating member on the shaft forconnection to the outer end of the wire. These and other objects andadvantages of the invention will be apparent from the followingspecification when taken with the accompanying drawing in which:

Fig. 1 is a rear elevation, with parts in section, ofva tuning assemblyembodying the invention; and

Fig. 2 is a side elevation of the same.

- In the drawing, the reference numeral l identifies the supportingplate uponjwhich'two permeability tuned circuits and the tuningmechanism therefor are mounted. The lower end! nals thus serving as thejunction points for connecting the coils into the receiver circuits.

Cores ll of finely divided magnetic material a and an insulating binderhave a fairly snug but of the plate is .reversely bent and spaced fromthe'bodyof theplate to form a rear support for the manual control shaft3. A second shaft 4 is journalled on the central portion of plate I andcarries a large diameter drum or pulley 5 that is connected to the shaftl by the usual flexible cable 8. I

Each tuned circuit includes a coil 1 in the form of a relatively longwinding on a small diameter tubular coil form of thin-walled insulatingmaterial. The-outer ends .of the coil forms are securely anchored tobrackets 8 that extend rearwardly from the supporting plate, and theirinner ends extend through and are accurately positioned by the extrudedsleeves 10 of brackets H. Trimming condensers i2 are mounted on theplate'l .and have terminals to which the ends of the associated coilsare connected, the termifree sliding fit within the bores of the coilforms 8. These coil'forms are preferably extruded or molded fromsynthetic resins to eliminate variation in size and to obtain a highlypolished inner wall surface. Each core II has secured thereto,preferably by embedding therein, one end of relatively stiff butresilient coupling member It. These coupling members are preferablypiano wire of about 0.022 inch diameter. This material is suihcientlyrigid, in an axial direction, to move the core into the coil forms whenpressure is exerted on the outer ends of the wires, butcan flexlaterally to some extent to permit some variation in the direction of anapplied pull or push for adjustment of the core.

, The outer ends 15 of the wires H are bent to form open eyes that seatin the grooved sections of disks it on the ends of crank arms I! that,are secured to the shaft 4.

g The dimensions of the open eyes II are preferably suchthat the .wiresgrip the disks l8 tightly to prevent backshaft 4, the crank arms l-I maybe a single bar,

that is secured to the end of the shaft I.

, The parts are shown in solid line in Figs. 1 and 2 in the positionsthat they occupy when the cores ii are midway between their endpositions.

The crank arms I! are normal to the axes of the associated coil formsand may move about 45 to either side into the illustrated dotted linepositions. The angular motion of the adjusting shaft 4 is thus limitedto but it is desirable to indicate the tuning adjustment by a pointerthat moves through a larger angle. The shaft 4 therefore carries thelarger element of a motionmultiplying gearing is, the smaller gear being.on the shaft II which carries a pointer 20. The

shaft I 9 is rotatably' supported by the plate I and a strap 2| that issecured to the supporting plate; The illustrated gearing has a 2 to 1ratio and the pointer has oppositely directed arms for movement alongscales 22 that each extend over an arc of 180. Other ratios may be used,if desired, to spread the scale up to about 330.

The coils 1 may be the antenna and a radio frequency circuit in a tunedradio frequency receiver, or the antenna and the oscillator tuning coilin the case of a superheterodyne receiver. The wire employed ispreferably a multistrand cable, for example 10/42 single Celanese"enamel wire, the windings being of the progressive universal type. Goodresults have been obtained when the axial length of the coilapproximates the length of the core. Cylindrical cores of diameter and 1long have covered the range or 1700 to 540 kilocycles with a travel of 1inches, the Q value for the coil being fiat at approximately 100throughout the range.

Other means may be employed for securing the actuating wire to a core,or a plurality of cores, and for coupling the wire to the rotary controlshaft. It is therefore to be understood that various changes may be madein the parts of the tuning unit, their design, shapes and relativelocations without departing from the spirit of my invention as set forthin the following claim.

I claim:

In a radio receiver, a permeability tuned circuit comprising a tubularcoil form, a coil on said form, a magnetic core slidable in said coilform, a length of piano wire having one end rigidly secured to saidcore, and tuning means,

for adjusting said core; said tuning means comprising a shaft carrying acrank arm, a member rotatably mounted on the outer end of the crank arm,the other end of said piano wire having the form of an open eyeextending. about and resiliently held to said member.

JOHN V. FILL.

